Inclusion complex of magnolol with hydroxypropyl-β-cyclodextrin: characterization, solubility, stability and cell viability

Abstract

The objective of this study was to investigate the effect of hydroxypropyl-β-cyclodextrin (HP-β-CD) on the water-solubility and stability of magnolol (MAG). The inclusion complex was prepared by a coevaporation strategy and the interactions of MAG with HP-β-CD were investigated using powder X-ray diffraction, ultra violet–visible spectroscopy, 1H nuclear magnetic resonance spectroscopy, 2D NMR spectroscopy, molecular modeling, Fourier transformation-infrared spectroscopy, scanning electron microscopy and phase solubility studies. All the characterization information proved that MAG was able to form an inclusion complex with HP-β-CD (MAG-HP-β-CD). The inclusion complex had a stoichiometry of 1:1 and the stability constant (K c) was calculated to be 2, 206 M−1. The aqueous solubility of MAG increased more than 500-fold and the stability of MAG was notably increased in the presence of HP-β-CD. Furthermore, preliminary in vitro cytotoxicity assay showed that MAG-HP-β-CD exhibited enhanced anti-cancer activity compared with free MAG. This satisfactory water solubility and stability of MAG-HP-β-CD inclusion complex will be potentially useful for its application as anti-cancer agent or healthcare products.